"[It's] extremely heavily vegetated and wooded, and for the guys to get from the pinnacle where I dropped them off on the winch down to the crash site, which is only about 150 metres away, took them at least 15 to 20 minutes to get there... it's that heavily vegetated," he said.

Crews treated the sole survivor at the scene for a shoulder injury.

He has been flown to Rockhampton hospital.

The Australian Transport Safety Bureau is investigating the cause of the accident.

Three investigators and two ADF experts are expected to arrive at the scene on Friday.